Consequentialism is an array of ethical theories which hold that the goodness or rightness of an action is to be measured by the sum of all its outcomes. It is one of the two most major strands of contemporary ethics. The other, deontology, measures the morality of an action by its compliance to given rules and moral precepts, that must be followed above all else.

The consequentialist analysis can take the form of a utility function, where the expected utility of an action is determined by the sum of the utility of each of its possible consequences, individually weighted by their respective probability of occurrence. Therefore, the correct action is always the one which maximizes o total value of positive consequences, even if it violates some established moral rule. Consequentialism is based on a cost and benefits analysis and measure goodness by calculating the total expected good. In this manner, opposing to deontological theories, there is no action good in itself or bad in itself, they have to be judged by its results. Note, however, that consequentialism is not the same thing as having a utility function, since utility functions can also be used to implement moral theories similar to deontology.

Which outcomes are to be considered good or bad is an open question to consequentialism. Hence, one can egoistically value his own well fare in detriment of others and still act according to a consequentialist ethics. Utilitarianism can be seen as instance of consequentialism where one must aim at maximizing the overall good, the happiness and welfare of himself and others.

One common tool for detecting a person way of thinking about morality is the use of moral dilemmas, in special the trolley’s problems. Those problems have generated a vast array of moral dilemmas of hard resolution and justification. They usually follow a general schema: “Person A can take an action which will benefit a great number of people, but that also violates moral rule X or person’s B individual rights. What should person A do?” Taking the action reveals a consequentialist thinking, whereas holding to the moral rule reveals a deontological thinking.